Using 2- and 21/2-dimensional seed filling in view lattice to accelerate volumetric rendering

In this paper we propose new methods for calculating the projection of an o paque 3-dimensional B-connected volumetric object into a two-dimensional vi ew using 2- and 2 1/2-dimensional seed-filling in the view space. When a 3- dimensional volumetric data set is sampled by parallel rays at a resolution exceeding the Nyquist ratio, the 6-connectivity of objects is maintained f rom volume lattice to view lattice. Given a seed point for each 6-connected object in the volumetric data set, a seed-filling algorithm may access all sample points in view lattice, while simultaneously composing the rendered view. The algorithms presented in this paper minimize the number of voxels that need to be processed. We implemented these methods on a general purpo se computer architecture and tested them with several artificial and real-l ife medical volumetric data sets. It is shown that the algorithms may be us ed to speed up the parallel ray casting of opaque medical objects. The actu al frame rate achieved by the combined method allows interactive (10 frames /sec) rotation of the object on a common single-processor personal computer without specialized hardware. (C) 1999 Elsevier Science Ltd. Ail rights re served.